The present invention relates to the field of read/write head suspensions for disk drives, more particularly to a gimbal and load beam arrangement for carrying a head slider in such head suspensions.
Gimbals for head suspensions are required to maintain the read/write head at a desired orientation to a rotating disk with which they cooperate to read and write data with respect thereto. It is desirable to have compliance or flexibility in both roll and pitch dimensions for such heads, to allow the head to follow variations in the disk surface. At the same time, it is desirable to have the gimbal and overall head suspension be relatively stiff in a lateral dimension to enable accurate tracking and fast response times to slew commands calling for a track change.
Prior art designs typically had a stainless steel layer in a pair of gimbal arms, providing sufficient lateral stiffness, at the expense of reduced flexibility in the roll and pitch dimensions. One attempt to address these conflicting requirements was a gimbal and head suspension referred to as FgSA from Innovex, at 5540 Pioneer Creek Drive, Maple Plain, Minn. 55359. The FgSA product had low pitch and roll stiffness, since the gimbal arms had no stainless steel backing. The FgSA product was attached to a load beam by glue at proximal and distal ends of the gimbal. Absence of stainless steel in the FgSA product prevented welding of the gimbal to the load beam, and increased the difficulty of bonding the head after flexure attachment. Another approach is shown in U.S. Pat. No. 5,844,751, assigned to the assignee of the present invention. In this patent, the stainless steel layer is omitted, resulting in low pitch and roll stiffness, but also with low lateral stiffness.
The present invention overcomes shortcomings of the prior art by providing a gimbal and load beam arrangement with a structural layer, preferably stainless steel, but with the structural layer omitted from the lateral arms of the gimbal, and wherein the gimbal is joined to the structural layer at locations distal and proximal of the gimbal region, to provide both low stiffness for pitch and roll dimensions, while simultaneously providing high stiffness in the lateral dimension. The present invention further provides a central portion of the structural layer intermediate the proximal and distal locations to enable formation of a raised load point and to ease the difficulty of attaching the head after the gimbal is attached to the load beam. In present assemblies, the slider is attached adhesively, and then gold balls (using ultrasonic bonding) or solder is used to connect the head to the copper conductors on the gimbal. A further advantage is that when the structural layer is formed of stainless steel, it may be extended proximally of the load beam portion to form a spring region for the head suspension assembly between the load beam portion and the base plate. Finally, having a metal layer at the location distal of the gimbal enables inclusion of a headlift member into the design, and may include a layer of dielectric on the headlift, avoiding or reducing the potential for contamination of the disk drive environment with particles abraded off the load/unload ramp by the headlift.